import scipy.stats as ss
import numpy as np
# 1、已知总体标准差求期望
mean = 12168  # 样本均值
std = 2200  # 总体标准差
n = 480  # 样本数量
alpha = 1 - 0.95
z = ss.norm.isf(alpha / 2)
ME = z * std / np.sqrt(n)
up = mean + ME
low = mean - ME
print("({0},{1})".format(round(low, 5), round(up, 5)))  # 保留五位
